When you create or edit a linked-clone desktop pool, the Select Datastores page displays a table that provides storage-sizing guidelines. The table can help you to decide which datastores to select for the linked-clone disks.

Sizing Table for Linked-Clone Disks

Example Sizing Table for Linked-Clone Disks shows an example of storage-sizing recommendations that might be displayed for a pool of 10 virtual machines if the parent virtual machine has 1GB of memory and a 10GB replica. In this example, different datastores are selected for OS disks and View Composer persistent disks.

Example Sizing Table for Linked-Clone Disks

Data Type

Selected Free Space (GB)

Min Recommended (GB)

50% Utilization (GB)

Max Recommended (GB)

OS disks

184.23

40.00

80.00

130.00

Persistent disks

28.56

4.00

10.00

20.00

The Selected Free Space column shows the total available space on all of the datastores that you selected for a disk type such as OS disks.

The Min Recommended column shows the minimum amount of recommended storage for a pool.

The 50% Utilization column shows the recommended storage when the linked-clone disks grow to 50% of the parent virtual machine.

The Max Recommended column shows the recommended storage when the linked-clone disks approach the full size of the parent virtual machine.

If you store OS disks and persistent disks on the same datastore, View Manager calculates the storage requirements of both disk types. The Data Type is shown as Linked clones instead of a particular disk type.

If you store View Composer replicas on a separate datastore, the table also shows storage recommendations for the replicas and adjusts the recommendations for OS disks.

Sizing Guidelines

The table provides general guidelines. Your storage calculations must account for additional factors that can affect actual storage growth in the linked-clone pool.

For OS disks, your sizing estimates depend on how frequently you refresh and recompose the pool.

If you refresh your linked-clone pool between once a day and once a week, make sure that the Selected Free Space can accommodate storage use between the Min Recommended and 50% Utilization estimates.

If you rarely refresh or recompose the pool, the linked-clone disks continue to grow. Make sure that the Selected Free Space can accommodate storage use between the 50 % Utilization and Max Recommended estimates.

For persistent disks, your sizing estimates depend on the amount of Windows profile data that users generate on their desktops. Refresh and recompose operations do not affect persistent disks.

How View Manager Calculates the Minimum Sizing Recommendations

To arrive at a minimum recommendation for OS disks, View Manager estimates that each clone consumes twice its memory size when it is first created and started up. If no memory is reserved for a clone, an ESX swap file is created for a clone as soon as it is powered on. The size of the guest operating system's paging file also affects the growth of a clone's OS disk.

In the minimum recommendation for OS disks, View Manager also includes space for two replicas on each datastore. View Composer creates one replica when a pool is created. When the pool is recomposed for the first time, View Composer creates a second replica on the datastore, anchors the linked clones to the new replica, and deletes the first replica if no other clones are using original snapshot. The datastore must have the capacity to store two replicas during the recompose operation.

By default, replicas use vSphere thin provisioning, but to keep the guidelines simple, View Manager accounts for two replicas that use the same space as the parent virtual machine.

To arrive at a minimum recommendation for persistent disks, View Manager calculates 20% of the disk size that you specify on the View Composer Disks page of the Add Pool wizard.

Note

The calculations for persistent disks are based on static threshold values, in gigabytes. For example, if you specify a persistent disk size of any value between 1024MB and 2047MB, View Manager calculates the persistent disk size as 1GB. If you specify a disk size of 2048MB, View manager calculates the disk size as 2GB.

To arrive at a recommendation for storing replicas on a separate datastore, View Manager allows space for two replicas on the datastore. The same value is calculated for minimum and maximum usage.

After you estimate storage requirements, select datastores, and deploy the pool, View Manager provisions linked-clone virtual machines on different datastores based on the free space and the existing clones on each datastore.

Based on the storage-overcommit option that you select on the Select Datastores page in the Add Pool wizard, View Manager stops provisioning new clones and reserves free space for the existing clones. This behavior ensures that a growth buffer exists for each desktop on the datastore.

If you select an aggressive storage-overcommit level, the estimated storage requirements might exceed the capacity shown in the Selected Free Space column. The storage-overcommit level affects how many virtual machines that View Manager actually creates on a datastore.